What is the best place to make a connection for a 12 volt source (on only when the ignition key is on) on a 2003 Explorer? I want to install a special radio. I want to hardwire it, not use the lighter plug. My last vehicle had a few spare connection points right on the fuse panel, but this one seems not to have that, even though Explorers get used for emergency vehicles, etc.
Any other good places to make such a connection that anyone has used?

There should be two fuse panels, one under the hood (check for spare fuse/port not being used) and a smaller fuse panel under the dash (drivers area). As jwko mentioned, if you're going to be running more than 20amps regularly it's not advisable to use a fuse, run it straight from the battery. The majority of 12V sockets will handle up to 20amps. If you want to hard wire it and don't use the cig lighter, you can splice into the wiring behind the dash and use that connection for the radio. If you do, I would make sure that the current draw is not greater than 5amps just to be safe in overheating the wiring.

Don't forget that emergency vehicles are specified before they leave the factory, so they are built a bit differently with some extra options & deletions.

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